Thinking about a 4 Blade Propeller....
1. SELECT A PROPELLER from the Propeller Blade Selection Table that most closely matches the pitch and diameter of your current propeller (typically found on the propeller hub). If you have a 3 blade propeller and wish to switch to a 4 blade propeller, choose a propeller from the table that is one pitch size smaller than the one you are currently running.
2. SELECT A QL INTERCHANGEABLE HUB KIT from the table that fits your Outboard or Sterndrive engine to make your installation complete. The 'Prop Series' of both the Propeller Blade and Interchangeable Torsion Rod Hub Kit should match.